These insects, whose ears are each only about the size of a pinhead, can recognize sounds between 30 and 300 kilohertz (kHz)—a range never before seen in the animal kingdom.

A greater wax moth rests in England in 2007. Photograph by Andrew Darrington, Alamy

People speak at about 3 kHz. In youth we can hear up to about 20 kHz, but we lose our ability to recognize higher frequencies as we age. Dogs generally hear frequencies of about 30 kHz. But nothing compares to the moth’s 300-kHz extreme.

Since there aren’t any sounds in nature that come close, scientists hypothesize that greater wax moths evolved supersensitive ears to evade bats, their main predators. (See “‘Whispering’ Bat Evolved to Trick Prey.”)

“I think it’s a really amazing study,” said Damian Elias, a biologist at the University of California, Berkeley, who wasn’t involved in the experiment.

“Biologists make assumptions as to what types of sounds and frequencies animals should hear,” he said, but ”when you actually measure it, you’re often surprised.”

No Words to Explain It

To test the moths’ hearing, the scientists built special speakers that played increasingly higher frequencies. The team then used a laser to measure the moths’ ear movements in response to each frequency. They also assessed the electrical nerve signals sent from the moths’ ears to their brains.

These two calculations indicated whether the moths’ ears were responding to individual sounds. The results showed that the moths ended up topping out at about 300 kHz—a pitch so high that even researchers have a difficult time understanding the pinnacle.

“The problem is that because humans don’t hear that sort of frequency, we don’t have any words for it,” said study co-author James Windmill, an acoustical engineer at the University of Strathclyde in Scotland.

“There’s not that much that happens in nature that happens at those frequencies.”

Bat vs. Moth

Bats are the only animals that come close, with a hearing capability of about 212 kHz. Windmill and his team hypothesize that moths—found throughout much of the world—use their highly acute hearing to avoid bats that see them as tasty snacks.

Listen to a silver-haired bat attack an insect.

The two groups have been locked in an evolutionary arms race for generations, each trying to best the other by evolving new traits to hunt and evade. Right now, the moths are winning, said Windmill, whose study was published May 8 in Biology Letters. (Related: “Moths Jam Bat Sonar, Throw the Predators Off Course.”)

 The advantage is a matter of physics, where response time and frequency are closely tied. Since moths are able to hear such high pitches, they have the ability to react to lower pitches much faster. Moths listen for a bat’s ultrasound pulses and take evasive action. (Interactive: Hear tropical bat calls.)

Moth Ears Could Inspire New Tech

Compared with a human ear, the moth ear is incredibly simple, consisting of just a few nerve cells that feed directly into the brain. The natural system is so unique that Windmill says he’s working with the military and hopes to develop microphones based on the design.

More sensitive microphones could be adapted for hearing aids and cell phones, which have what’s called the “cocktail-party problem.”

Whereas human ears are able to pick out and focus on one conversation even when there’s a lot of background noise, the microphones on most devices aren’t as targeted—meaning that Windmill’s moth-ear study could be the catalyst for technological breakthroughs. (Also see “Urban Grasshoppers Sing Louder.”)

“Evolution is a great inspiration for scientists,” noted the University of California’s Elias.

“Animals have remarkable capabilities to sense things,” he said. “They’re able to do things that human hearing and human-engineered devices are very poor at doing.”

And when its prey dives into cracks and crevasses within a coral reef, the grouper uses its own version of sign language to get help, a new study says.

The fish enlists the assistance of two other predators, the giant moray eel and the Napoleon wrasse, waiting up to 25 minutes for one to come into sight.

A coral grouper near a scuba diver in the Red Sea. Photograph by Reinhard Dirscherl, WaterFrame/Getty Images

When one does, the grouper points its nose toward the concealed prey and starts to shake its body from side to side. This signal is the equivalent of ringing a dinner bell—food is here!

That’s when the interspecies killing team goes to work. The wrasse is the strongman, smashing into the reef and breaking it apart—forcing its prey to flee or get pulverized.

“[Wrasse] have a very powerful jaw, and they can destroy holes that aren’t well constructed,” said study co-author Redouan Bshary, a behavioral ecologist at the Université de Neuchâtel in Switzerland. “They can break coral.”

“Prey will evacuate holes just to avoid getting smashed together with their hiding place,” added Bshary, who observed the behavior during scuba diving research trips to the Red Sea.

While less destructive, morays are no less deadly. Their slim bodies allow them to squeeze into the crevasse to track the prey within. If the fish manages to escape both both wrasse and moray, then the grouper gets one more shot at a meal. (Also see “Herring Break Wind to Communicate, Study Suggests.”)

“Now, while they’ve learned to cooperate, fish don’t share,” Bshary noted. “Whoever gets the prey, swallows it whole.”

Even with multiple parties competing for one food source, groupers are more successful in a group. (See a picture of a goliath grouper.)

When hunting alone, groupers only catch their prey about 1 out of every 20 attempts, Bshary said. When they have help, the ratio is significantly better—about one out of seven, he added.

Group Hunt

Groupers can also use sign language as a call to action. Sometimes before prey has been sighted, groupers will approach a wrasse and moray and shimmy, which translates into a request for a team hunt. The trio will scour the ocean, each utilizing their own unique skill sets. (See pictures of ocean animals’ survival skills.)

“They all go hunting together,” said Bshary, whose study appeared April 23 in Nature Communications. “It looks quite impressive when they come all together and start inspecting.”

Scientists still haven’t figured out why groupers are able to communicate with other species. While people, apes, and some birds are adept at signaling, the scientific community previously thought a fish’s tiny brain wasn’t up to the task.

Bshary and his team have logged a lot of hours underwater to study the grouper’s odd disco, braving pruny fingers and wicked sunburns.

“There’s this idea that you need a large brain to use referential gestures, [but] even a fish with a rather standard brain shows this ability to produce referential gestures,” Bshary said. “This is important. It’s decoupling cognitive abilities from brain size.”

The next step, he said, is to repeat the experiment with the species within the lab to see what other secrets the grouper’s strange signs may unlock.

But what these artificial insects lack in processing power, they make up for in efficiency: Robotic ants can automatically choose the shortest route from their food sources back to their nests, just like real ants, a new study says. This gives valuable insight into how people should plan transportation and communication systems.

“It’s really interesting to look at social insects because [they] can give us a way to manage information in our societies,” said Guy Theraulaz, a behavioral biologist at the National Center for Scientific Research in France, a co-author on the study. “We take some inspiration from nature.” (Related: “Color-Changing Rubber Robot Could Aid Animal Study.”)

Robo-ants aren’t so different from the insects they mimic. Real ants have tiny brains, which means navigating everyday life, with all its sights and vibrations, is a challenge. So to save brainpower, these insects have evolved to ignore outside stimulation.

“Ants are pretty dumb by themselves,” said study leader Simon Garnier, a biologist at the New Jersey Institute of Technology’s Swarm Lab. “They have about a hundred thousand neurons. There are more neurons in your finger.”

The Path Most Efficient

Despite their simplemindedness, ants almost always take the most efficient path home, which has long stumped the scientific community.

So Garnier and colleagues programmed tiny robots to act like ants using a series of simple computer commands and then put them in a labyrinth. When the robot ants reached a fork in the road, they kept walking straight until they hit an obstacle and veered off in the direction of least resistance—the shortest distance. The ants were relying on simple physics.

“If I blindfold you and put you in the corridor, and you hit the wall, you’re more likely to take the path that deviates less,” said Garnier, whose study was published March 28 in the journal PLOS Computational Biology.

Once the robot ants find the most efficient way through the labyrinth, they alert their peers by calling attention to the pathway with lights. (Real ants use pheromones, or chemical markers.) The robot ants go marching one by one, each laying down a new layer of light. Soon, all ants are traveling on the same, highly productive road. (Watch a video of fierce army ants.)

“It’s like if you want to go to a restaurant with your friends, and one says, ‘I want to go to pizza.’ The other says, ‘I want to go to Chinese food.’ And at one point, if more friends say they want to go to pizza, you’ll go there,” Garnier added.

Combating “Collective Madness”

It’s called the “ant algorithm,” and our societies could benefit from applying it to everyday problems. (Also see “Could Cyborg Cockroaches Save Your Life?”)

Like ants, “we are overloaded with information, but we didn’t develop the appropriate filter,” said Theraulaz, of the French scientific center. “Now we produce a kind of collective madness, and that’s the problem.”

Adopting more collective-swarm intelligence would also make human society less costly and more productive, Theraulaz said. For example, thinking like an ant swarm could better plan shipping routes, place cell phone towers, and task assignments within companies.

The next step is to build more robot-ant studies to further test the algorithm and then apply it to large-scale systems, such as city planning and freeway mapping.

“We can build very simple entities,” Theraulaz said. “This kind of technology will invade society and promote collective intelligence.”

Without status updates and hashtags, these ocean dwellers—named for their yellow hues—actively keep in touch with and transfer knowledge between themselves and other sharks, according to scientists with the Bimini Biological Field Station, which is located in the Bimini Islands (map), near the Bahamas.

A group of lemon sharks is called a shiver. Photograph courtesy C.J. Crooks

“They basically have friends,” said Tristan Guttridge, a behavioral ecologist at the station. “They have individuals that they prefer to follow and have social interactions with.” (See another picture of a lemon shark in the Bahamas.)

Social living is a common practice within the animal kingdom that provides well-known evolutionary advantages. For instance, thanks to multiple eyes on the lookout for food and predators, animals that stay together often have higher rates of survival when compared with loners.

So it makes sense that lemon sharks would take advantage of safety in numbers and create shivers—the shark version of a flock or pack. (Also see “Lemon Sharks Swarm Florida ‘Lovers Lane.’”)

But when Guttridge took lemon sharks out of the wild and put them into captivity—eliminating their need to hunt for food and stay wary of threats—the sharks still made an effort to socialize.

“As humans we associate sociality with whales,” Guttridge said. “You don’t often think a shark would be like that—you expect them to be very territorial and aggressive to each other. [Yet] we never see aggression between individuals” of a lemon shark group.

The Social Life of a Shark

For his previous research, Guttridge captured 42 juvenile lemon sharks from waters off the Bahamas, placing them in square test pens.

These 10-meter-by-10 meter (33-foot-by-33-foot) confinement areas were divided into two outer compartments and a central area. Researchers ran a series of experiments, placing varying numbers of lemon sharks in the outer pens and one in the center. Lemon sharks were given the opportunity to interact with their species in the compartments or remain alone. (See more shark pictures.)

A lemon shark is seen from below. Photograph courtesy C.J. Crooks

It turns out that lemon sharks can actually be friendly, according to the research, published in 2009 in the journal Animal Behaviour.

Researchers found that sharks spent significantly more time in the compartments closest to other sharks, even though there was no survival advantage—meaning they wanted to spend time together, Guttridge said.  (Also see “Sharks Travel ‘Superhighways,’, Visit ‘Cafes.’”)

“We had an individual in the middle of the pen, and it could swim anywhere it wanted to, but it would always spend more time on the side with other individuals,” he added. “There wasn’t any predation risk. They weren’t getting any more food. They just had this social attraction.”

Sharks of a Fin Stick Together

But, compared with other species of shark, lemon sharks are selective about their social circles. They’re much more likely to pal around with sharks their own size, said Jean-Sebastien Finger, a biologist at the Bimini field station. This gravitation toward similar body types is common within nature: After all, birds of a feather flock together, so it makes sense that sharks of a fin would form a shiver.

Such a specific attraction is likely a survival technique, Sebastien-Finger added, since sharks of similar sizes eat the same types of food and must avoid the same predators. (Also see “Pictures: Biggest Whale Shark ‘Swarm’ Found.”)

“It’s fairly complex, these rules of group behaviors and laws of attraction and avoidance,” behavior ecologist Guttridge said.

Swim With Me, Maybe?

Being picky about your friends is also important for passing on knowledge—you can’t leap with the dolphins if you’re lurking with the bottom feeders, for instance. Lemon sharks learn from observing others, according to the recent research, published in 2012 in the journal Animal Cognition.

“They can learn from each other and transfer information,” Guttridge said. (Read about National Geographic Grantee Samuel Gruber, head of the Bimini station.)

For the newer study, scientists trained a group of lemon sharks to hit a target, rewarding their successes with food. These learned sharks were paired with sharks that hadn’t had any instruction.

Lemon sharks (pictured near the Bahamas) are very sociable. Photograph courtesy C.J. Crooks

When asked to perform the task later, the newbie sharks completed more trials with a higher rate of success than the control group. This suggests that sharks can use social interactions as opportunities to learn how to find food, identify predators, and woo mates.

“It’s almost like school for us,” Guttridge said. “You learn how to interact with other people. Maybe these sharks are learning how to interact with each other, and as they get older it helps with reproduction.”

A shark’s idea of courtship might not include a declaration of love on Facebook, but this species doesn’t mature until they’re well into their teenage years—plenty of time to study up, Guttridge adds.

Social Suicide

However, there’s a cost to being social. Lemon sharks that hang out in groups have a higher risk of contracting parasites and diseases. If a friend is constantly sick, the benefits of pairing up for safety reasons don’t necessarily compute.

“Because you have more friends, you have less chance of being killed,” Finger said, but there’s also the possibility of disease.

These are tricky waters to navigate, and the Bimini team doesn’t have all the answers—but they say they’re determined to keep researching. (See shark photos submitted to National Geographic.)

Next up, the team will examine lemon shark personality. Though the findings are preliminary, individual lemon sharks show some signs of having specific mannerisms such as shyness, Finger said.

In shark terms, this means they’re much less sociable than normal. In human terms, it suggests they’d have but a few Facebook friends. In both worlds, it’d be social suicide.

The pitcher plant Nepenthes khasiana glows blue. Photograph courtesy Rajani Kurup, Anil J. Johnson, Sreethu Sankar, and Sabulal Baby

The flesh-eating flora have special cells that help them generate an ultraviolet hue, according to a new study published in the journal Plant Biology. Though invisible to the unaided human eye, the fluorescence is quite alluring to an inquisitive insect. (See pictures of killer plants.)

“To the best of our knowledge, this is the most distinct fluorescent emission found in the plant kingdom,” said study author Sabulal Baby, a plant biologist at the Jawaharlal Nehru Tropical Botanic Garden and Research Institute in India.

The glow is actually a survival technique: Carnivorous plants most often grow in nutrient-deficient soils and have to catch and kill bugs to supplement their poor diets.

Like Moths to a… Glow Stick

The plants’ light is emitted as an ultraviolet wavelength tailored to appeal to potential prey, including insects and other arthropods, the group that includes crustaceans, insects, and spiders. Insects often can see wavelengths that emphasize food sources.
For example, research suggests that honeybee eyes have evolved to pick out the brightest—and hopefully most nectar-rich—flowers.

The plant Sarracenia purpurea glows in UV light. Photograph courtesy Rajani Kurup, Anil J. Johnson, Sreethu Sankar, and Sabulal Baby

To an insect, the carnivorous plant’s glow probably looks like a bonfire. But to people looking at the plant under a black light, it’s something like a glow stick.

“In normal light, humans are not going to see this,” Baby said. “In the scale of a small ant, this could be a very clear light to them.” (Also see: “Glowing Animals: Beasts Shining for Science.”)

Fatal Attraction

Baby and his team examined four major types of carnivorous plants: pitfall traps, flypaper traps, snap traps, and bladder traps. Pitfall traps use pools of water or nectar to drown victims, while flypaper traps secrete sticky substances to snag a live snack.

Snap traps make some of the fastest movements in the plant kingdom, rapidly closing around prey, and bladder traps suck in prey using an internal vacuum. (Related: “Tentacled, Carnivorous Plants Catapult Prey Into Traps.”)

Only the pitfall traps Nepenthes and Sarracenia and the snap trap Dionaea muscipula generated the distinct blue emissions, which turned out to be important to the plants’ survival. For instance, when scientists blacked out the ultraviolet light, the predators were less likely to attract insects. (Also see “Spiders, Carnivorous Plants Compete for Food—A First.”)

The pitcher plant Nepenthes khasiana is seen in white light (left) and ultraviolet. Photograph courtesy Rajani Kurup, Anil J. Johnson, Sreethu Sankar, and Sabulal Baby

Though the research is incomplete, Baby also suspects that small animals like tree shrews and rats can also see the blue hue, enticing them to drink the plants’ sweet nectar. In the process, these animals drop fecal matter inside the plant, which becomes another good source of nutrients.

“The fluorescents are a very important attractant of insects, arthropods, and small animals,” he said.

Go With the Glow

Pitfall traps and snap traps aren’t the only plants to use ultraviolet frequencies. There are many species whose molecular makeup give them the ability to glow, said Howard Berg, a plant-cell biologist and the director of the Integrated Microscopy facility at the Donald Danforth Plant Science Center in Missouri.

“They have a chemical structure called conjugated double bond, and they have the ability to absorb light and re-emit it,” he said.

Fluids from a pitcher plant in the Nepenthes species fluoresce. Photograph courtesy Rajani Kurup, Anil J. Johnson, Sreethu Sankar, and Sabulal Baby

Berg added that the finding may even aid in future breakthroughs. Fluorescent jellyfish proteins are attached to specific markers, allowing researchers to study, for example, how cancer cells spread. The carnivorous plant’s glowing cells could potentially provide a new tracking method.

“It’s like a luggage tag,” Berg said. “You can use that as a locator. It’s really cool.”

What’s more likely, though, is the development of the ultimate bug zapper, study author Baby said.

The ultraviolet glow could work in tandem with an electric current to zap unsuspecting insects. The future of pest control—just go with the glow.

To the untrained eye, it looks like a case of movie magic, but scientists at Johns Hopkins University School of Medicine now have data to explain the eerie skill that has baffled birders for years. (Check out National Geographic’s backyard bird identifier.)

Whereas people and other animals can simply move their eyes to follow an object or use peripheral vision to scan a room, owls must turn their heads for the same effect. These birds have fixed eye sockets, which means their eyeballs can’t rotate, forcing them to stretch their necks—a seemingly supernatural feat.

“In the case of birds, their systems are designed to handle that amount of movement,” said Eric Forsman, a wildlife biologist for the U.S. Forest Service, who was not part of the study.

“The tissue, the blood vessels are designed to flex—things don’t just snap.”

Turning Heads

Owls are more flexible than humans because a bird’s head is only connected by one socket pivot. People have two, which limits our ability to twist, Forsman added. Owls also have multiple vertebrae, the small bones that make up the neck and spine, helping them achieve a wide range of motion.

Yet, even with these skeletal advantages, a bird’s body shouldn’t be able to withstand such extreme levels of movement. In people, a spinning head would cause all kinds of internal bleeding and breakage.

For the new research, the Johns Hopkins team obtained 12 dead birds from educational centers and created 3-D images of the animals’ blood vessels and bones. The scientists also injected the carcasses with dye and liquified red plastic to preserve their arteries before dissection, according to a summary of their research on the U.S. National Science Foundation website.

The team discovered owls have backup arteries, which offer a fresh supply of nutrients when blood vessels get closed off by rapid turning. Their arteries also swell to collect any excess blood created in the process.

Eerie Ability Not Unique

It’s a powerful adaptive trait, Forsman said, but it’s not unique. Plenty of birds have a similar ability to look behind them. Red-tailed hawks, for example, are almost as flexible as their nocturnal cousins.

“There are lots of advantages to being able to look over your shoulder and see something coming—if you’re trying to avoid predators or detect prey,” he said. (Watch a video of an owl hunting prey.)

Owls might not be distinctive within the animal kingdom, but they do have the corner on Hollywood horror flicks. With their bulbous eyes and haunting calls, these birds can swivel their way from one thriller to the next.

The head-turning study won first place in the Posters category of the 2012 International Science & Engineering Visualization Challenge.

The word “dermestid” derives from the Greek word meaning “skin,” and the insect is aptly named. These creepy crawlies will eat the flesh off carcasses in a process called skeletonization. (Also see “Flesh-Eating Caterpillars Discovered in Hawaii.”)

Dermestid beetles at work. Photograph courtesy Ken Hansen

Wildlife law enforcement agents use the beetles to expose skeletons when harsh chemicals might damage evidence, such as marks on bones. Museum curators and taxidermists also use the bugs to clean skeletons for research and displays. Hundreds of dermestid beetles are often used to pick a cadaver clean.

It’s a low-tech solution to an ordinarily high-tech problem, said Ken Hansen, a retired federal game warden with the U.S. National Oceanographic and Atmospheric Administration, who has been selling dermestid beetles for six years.

“I can recall one instance where they actually had a skull, and they were trying to clean the skull for a potential murder investigation, and the beetles were used to clean the skull,” he added. “There certainly is a use for these forensically.” (See “Museum Secrets Unmasked by ‘Museomics’ Technologies.”)

Dermestid beetles pick a skull clean. Photograph courtesy Ken Hansen

For those who can stomach the stench, it’s an incredibly engaging process—emphasis on the “gag.” Check out this viral video of parrot versus flesh-eating beetle—we’ll let you guess who wins. 

Beetles Be Eatin’

In the wild, the 12-millimeter-long scavengers decompose animals long since expired. But if you live in North America, they can also lurk in your walls or under floorboards.

Once indoors, the grubbers expand their palates. According to the U.S. Fish and Wildlife Service Forensics Laboratory, dermestids will eat their way through materials like old books, carpets, or woolens.

This appetite for anything organic sometimes makes them a nuisance for museum personnel and taxidermists. Though it’s rare, adult dermestids have been known to fly, and escapees that find their way into exhibits can do considerable damage.

Flesh-eating beetles on the loose sounds like an Alfred Hitchcock movie, but people need to worry more about their linens than their limbs. 

There’s an urban legend about the beetles getting out in large numbers and destroying things, Hansen said, but they don’t eat living flesh.

Or, at least, not that we know.

Get more bug news:

Vomiting Caterpillars Explained

Bugs’ Battle of the Sexes

Dung Beetles’ Favorite Poop Revealed

Mollie Bloudoff-Indelicato is a freelance science journalist who loves em dashes, ’80s music, and water policy. She has a master’s degree from the Columbia University Graduate School of Journalism with concentrations in science journalism, photography, and radio reporting. Contact her at news@mbloudoff.com, and follow her on Twitter at @mbloudoff.